I submitted my I485 in January, 2002. Got married in July, 2002. My wife submitted her I485 under my application.
My I485 was approved in February, 2004. My wife's I485 was approved in April, 2005.
I think your wife can submit her I485 application under your application as long as your I485 has not been approved yet.
What I said is the situation about two years ago, you may consult with your lawyer about this.